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APPLICATION NOTES CONT'D

Set Speed / Torque Mode – Commands controller to receive mode command – speed mode versus torque mode.

Send Contents: Command Tag followed by 8 bits of data [2 words].

Command Tag: 0x42

Data:

0x00 – Torque Mode

0x01 – Speed Mode

Response Contents: Response Tag only [1 word].

Response Tag: 0x43

Description: Commands the controller to receive whether the control loop will be torque control or speed control mode. Torque control

mode will control the output torque of the motor by using the RMS current through the windings as feedback. Speed control mode will

control the speed of the motor by controlling the torque using the current as well as speed from encoder as feedback. Will also disable

bridge and reset the Speed / Torque command to 0.

Default Data Value: 0x00

Set Speed / Torque Command – Commands controller to receive speed or torque direction and magnitude.

Send Contents: Command Tag followed by 16 bits of data [3 words].

Command Tag: 0x1A

Data: 0xD8F0 – 0x2710. 2’s compliment format.

Response Contents: Response Tag only [1 word].

Response Tag: 0x1B

Description: Commands the controller to receive the magnitude and direction of the torque / speed in 16-bit, 2’s compliment format. In

speed mode, the range will be to 10000 RPM. In torque mode, the range will be to 10 amps RMS. Positive values will command one

direction, and negative values the opposite direction.

Default Data Value: 0x0000

Get Measured Current – Get current measurement from controller.

Send Contents: Command Tag only [1 word].

Command Tag: 0x1C

Response Contents: Response Tag followed by 16 bits of data [3 words].

Response Tag: 0x1D

Data: 2’s compliment format.

Description: Commands the controller to send the current value that is calculated every PWM cycle. This value should fall between +/

-10A and will be an RMS value. If in torque mode, this should correspond with your torque command.

Default Data Value: N/A

Set Brake Mode – Commands controller to receive Brake command.

Send Contents: Command tag followed by 8 bits of data [2 words].

Command Tag: 0x20

Data: 0x01 – 0xFF

Response Content: Response Tag only [1 word].

Response Tag: 0x21

Description – Commands the controller to begin applying PWM brake signals to the output bridge and to reset the command and PID

history to 0. This is dissipative braking only, using the internal resistance of the motor windings and Back EMF to slow down the motor

and apply braking resistance to the shaft. Braking is achieved by turning on the bottom transistors of the bridge, regardless of shaft angle

of the motor, and using the shorting of the Back EMF voltage through the resistance of the motor windings, essentially shorting all

windings together. However, this can be harsh if not applied in a controlled way. Control is achieved by implementing PWM modulation

of the low side transistors. Increasing the duty cycle will increase the amount of time each cycle that the windings are shorted together.

An 8-bit word is sent to the controller telling how long the ramp time is for increasing the duty cycle, with each bit being equal to about

7.8ms. A data value of 1 would have a ramp time of 7.8ms and the full data value of 255 would be have a 2 second ramp time.

Default Data Value: N/A

8548-100 Rev. C 3/13